May Wong, Ming Chen, Bill Skamarock, Wei Wang
Mesoscale and Microscale Meteorology Laboratory, National Center for Atmospheric Research, Boulder, Colorado

The regional domain configuration of the Model for Prediction Across Scales (regional MPAS) has been available since version 7.0. The model governing equations in MPAS (whether as a global or regional model) are very similar to the advanced Weather Research and Forecasting (WRF-ARW) model. Model physics, however, are always evolving based on advances in our science and model development activities. For example, although the schemes are nominally the same in the ‘tropical’ and the ‘mesoscale reference’ suites in WRF-ARW and MPAS, respectively, different versions are used because of the different time of implementation. We begin by ensuring that the versions of the physics schemes used are ‘identical’. In our early comparison work however, despite using identical physics, differences in the model solutions remain. Here, we present results on the sources of these subtle differences and highlight proposed changes in the model implementation to ensure consistency in the physics configurations of the two models. We demonstrate that the WRF-ARW and regional MPAS simulations can give similar results but only if care is given to the details of these related model physics configurations. These proposed changes will be included in forthcoming model releases.